Conventional shielded high-speed data cables, such as shown in FIGS. 1A and 1B generally include two or more pairs of insulated conductors 101 wrapped by a longitudinally applied laminate 102 of metal foil on a polymer base, thus forming a shield. This structure has a drain wire 109 applied in contact with the metal foil, and is contained within a suitable jacket 106.
The above-described structure has been found to be inadequate for some applications due to excessive leakage, because the metal foil shield frequently develops pin holes or tears during manufacture and installation. Furthermore, the longitudinally applied metal foil shield does not adequately control the dielectric spacing between conductor pairs, or between the pairs and the shield, resulting in erratic performance characteristics of such cable.
Some manufacturers have attempted to solve the above-noted problem by using two longitudinally applied metal foil or polymer laminate 102 and 108 shields or a single laminate 110 helically applied with edges overlapping. However, these attempted solutions often prove to be inadequate, because these attempted solutions do not address the issue of adequately controlling the dielectric spacing between conductor pairs.